View Single Post
Old 01-11-2021, 08:30 PM   #13 (permalink)
Isaac Zachary
High Altitude Hybrid
 
Join Date: Dec 2020
Location: Gunnison, CO
Posts: 1,953

Avalon - '13 Toyota Avalon HV
90 day: 40.45 mpg (US)

Prius - '06 Toyota Prius
Thanks: 1,035
Thanked 538 Times in 432 Posts
Quote:
Originally Posted by serialk11r View Post
Nah, you didn't get what I was getting at. The FB25 has bad efficiency at low speed partially because Subaru just doesn't build very good engines, but it's still a low revving engine.

Because it's a low revving engine, you can't play with the VVT. On my old Scion FR-S with the Subaru FA20 engine, I was able to squeeze 1 extra mpg by setting the intake cam to max retard and retarding the exhaust cam a few degrees to maintain overlap for internal EGR. With a low revving engine and short duration cams, you can't reduce pumping losses effectively with this strategy.

I had the same experience with my FA20 btw, efficiency was abysmal below 1500rpm even after I leaned out the fuel map.
Interesting.

I've never had a Subaru but I've always gotten my best fuel mileage in the 1,000 to 2,000 RPM range, not 2,000 and up range. And that has been the case on a few different vehicles, not just one or two.

I wonder how that would be affected by load, as in pulse and gliding. Would keeping it at up over 2,000RPMs still be more efficient for pulse and gliding than at lower RPMs?
__________________
  Reply With Quote